1. Field
The present disclosure relates to semiconductor devices that have been configured to reduce generation of cracks by reducing a tensile stress, and methods of manufacturing the semiconductor devices.
2. Description of the Related Art
Nitride-based semiconductor devices may use a sapphire substrate. However, a sapphire substrate is relatively costly and has a relatively low electric conductivity. Also, the hardness of a sapphire substrate may make it relatively difficult for the manufacture of chips. Additionally, the manufacture of a relatively large sapphire substrate may be complicated by its tendency to warp at relatively high temperatures due to its relatively low heat conductivity in an epitaxial growth process. In order to reduce or prevent the above problems, nitride-based semiconductor devices using a silicon (Si) substrate, instead of a sapphire substrate, are being developed.
Since a Si substrate has a higher heat conductivity than that of a sapphire substrate and thus is not warped as much even at a relatively high temperature for growing a nitride thin film, a relatively large thin film may be grown on the Si substrate. However, when a nitride thin film is grown on the Si substrate, a dislocation density may be increased due to a mismatch of lattice constants, and a tensile stress may be generated in the nitride thin film so as to generate cracks due to a mismatch of thermal expansion coefficients between the nitride thin film and the Si substrate. As a method of preventing cracks from being generated, a compressive stress is applied to the nitride thin film to compensate for the tensile stress generated due to the mismatch of thermal expansion coefficients.